Sulfur-hydrocarbon slurry pipeline transportation containing an asphaltenic material

ABSTRACT

An improved method of transporting sulfur-liquid hydrocarbon slurries through pipelines without causing plugging or corrosion of the pipelines. The invention relates to an improved and novel process of preventing plugging and corrosion of pipelines transporting sulfur in the form of a sulfur-liquid hydrocarbon slurry by addition thereto of a small amount of an aqueous solution and an asphaltenic material.

United States Patent Inventor Mary Frances Vondrak Houston, Tex.

Oct. 30, 1968 Aug. 3, 1971 Shell Oil Company New York, N.Y.

Appl. No. Filed Patented Assignee SULFUR-HYDROCARBON SLURRY PIPELINE TRANSPORTATION CONTAINING AN l 56] lkelerences Cited UNITED STATES PATENTS 2,798,772 7/1957 Redcay 302/14 3,368,876 2/1968 Bailey,Jr 302/14 Primary Examiner-Andres l-l. Nielsen Attorneys-George G. Pritzker and J. H. Mc Carthy ABSTRACT: An improved method of transporting sulfurliquid hydrocarbon slurries through pipelines without causing plugging or corrosion of the pipelines.

The invention relates to an improved and novel process of preventing plugging and corrosion of pipelines transporting sulfur in the form of a sulfur-liquid hydrocarbon slurry by addition thereto of a small amount of an aqueous solution and an 'asphaltenic material.

I SUlLl UR-MYDROCARWUN SLURI RY IPIIIPELIINIE TRANSPORTATION CONTAINING AN ASIPIHIAILTENIC MATElI-RIAIL BACKGROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurry in pipelines is well known in the art as noted by reference to U.S. Pat. Nos. 2,798,772; 2,9l 7,345 or 2,947,578 or as described in Pipeline Industry, June 1967, pages 58-60. In making the sulfur into a sulfur-hydrocarbon slurry, the sulfur is generally sprayed in molten form into either water or a hydrocarbon to form a slurry suitable for transportation through a pipeline. Formation of a stable slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, separation of the sulfur from the carrier fluid, plating or coating of the sulfur on pipeline walls causing plugging of the pipeline, corrosion, viscosity changes due to pressure and temperature variations encountered requiring increases in pumping power which increases operation costs, etc., are only a few of the problems normally encountered in transporting sulfur-liquid hydrocarbon slurries through pipelines.

Although the above are serious problems for consideration in transporting sulfur through pipelines, nevertheless the transportation of sulfur in slurry form through pipelines can be made to be an effective, attractive and economic means of transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for pipeline transpor' tation of sulfur slurries such as injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur slurry for pipeline transportation. Such means for transporting sulfur generally do not overcome the corrosion, coating and/or plugging problems described above.

An object of the present invention is to transport sulfur as a sulfur-liquid hydrocarbon slurry through pipelines which is stable and flowable:

Another object of the present invention is to transport through a pipeline sulfur-liquid hydrocarbon slurries without causing sulfur coating, deposition or plugging or corrosion of the pipeline.

Still another object of this invention is to form a slurry of sulfur in a liquid hydrocarbon medium, which when formed is stable, noncorrosive, does not tend to cause pipeline plugging when said slurry is transported through a pipeline and from which the sulfur can be readily recovered as essentially pure sulfur.

Another object is transfer sulfur as a liquid hydrocarbon slurry by pipeline over great distances reducing pumping and handling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to an improved, novel and new technique for transporting a sulfur-liquid hydrocarbon slurry through pipelines over great distances without causing corrosion, coating, deposition or plugging of the pipeline due to the tendency of sulfur under such conditions to adhere to the pipeline walls because of temperature, pressure and other variable conditions to corrode and plug said lines; by admixing or adding or injecting prior to or after injection of a sulfur liquid hydrocarbon slurry into the pipeline, a small amount of from 0.1 to percent by weight, preferably between about 0.5 to about 5 percent by weight, of an aqueous solution basis total slurry and from about to about 5000 ppm. basis oil phase of an asphaltenic material extracted from crude oil by any suitable means or an asphalt containing 20 to about 5000 ppm. basis oil phase of asphaltenic material. Asphaltenes can include materials described in "The Chemical Consistutents of Petroleum"-Sachanen, Chapter '9 and include petroleum resins, asphaltenes, asphaltogenic acids their derivatives and mixtures thereof and include materials described in the Journal of the Institute of Petroleum, Apr., 1968, pages l07l l4 and Feb., I968, pages 50 53 or as described in U.S. Pat. Nos. 3,275,076; 3,284,340 or 3,336,146 and these materials can be separated from petroleums by methods described in U.S. Pat. Nos. 3,364,138 and 3,368,876. The: asphaltenes as defined should be present in the final mixture in an amount preferably not exceeding 2000 ppm. basis oil phase and the additive can be injected when necessary in various places along the pipeline where indications are that corrosion or plugging of the line might take place. Any corrosion and plugging detection means known in the art can be used for this purpose. It has been noted that by injection of 1-5 percent by weight of an aqueous solution basis total slurry and a small amount (20-2000 p.p.m. basis oil phase) of an asphaltene as defined into a pipeline transporting a sulfur-liquid hydrocarbon slurry in which the sulfur content of the slurry can vary from 20 about 10 percent by weight to about '75 percent by weight or higher, preferably between 30 and percent by weight sulfur, inhibits corrosion and prevents plugging of the line due to sulfur deposition on the walls of the pipeline, resulting in improved flow of the slurry at reduced pumping cost. A preferred plugging and corrosion preventing composition for sulfur-liquid hydrocarbon slurries being pipeline transported is the addition to such slurries of from about 1 to 5 percent by weight water basis total slurry and 20-2000 p.p.m. basis oil phase of an asphaltenic material selected from the group consisting of asphalt, asphaltenes, asphaltogenic acid and mixtures thereof.

The sulfur-liquid hydrocarbon slurry can be made by any suitable means such as described in U.S. Pat. No. 2,798,772 or by the method described in copending U.S. Pat. application Ser. No. 663,755 filed Aug. 28, 1967 which matured as U.S. Pat. No. 3,443,837. It is preferred that methods for making the sulfur-liquid hydrocarbon slurry be used in which the sulfur is produced in spherical form since this facilitates the stable dispersion and suspension of the sulfur in the liquid hydrocarbon carrier and inhibits attrition and reduces friction. The phase transfer method for making the sulfur slurry as described in the above copending application comprises first forming a sulfur-aqueous liquid (water) slurry and thereafter phase transferring the sulfur particles from the aqueous liquid into a liquid hydrocarbon. In this process the phase transformation to form the sulfur-hydrocarbon slurry can be so controlled that a small amount. (l5percent by weight) water basis total slurry is transferred with the sulfur-water phase into the hydrocarbon phase and thereafter an asphaltenic material can be added to accomplish the desired! ends of the present invention.

The hydrocarbon carrier for the sulfur can be any liquid hydrocarbon ranging from a liquid petroleum fraction such as liquefied petroleum gas (LPG), fuel oil, gasoline, kerosene, petroleum distillates, condensates, crude oil and mixtures thereof. Preferred are liquid hydrocarbons containing at least 10 percent by weight or higher of aromatics, preferably about l5-30 percent by weight aromatic enriched kerosene or crude oil or crude oil condensate fractions containing l5-20 percent by weight aromatics which include monoand polyaromatic hydrocarbons.

At the terminal end of the line the aqueous solution can be readily separated from the sulfur-hydrocarbon system by suitable phase separation, distillation or the like.

PREFERRED EMBODIMENT OF THE INVENTION 40-60percent by weight sulfur in (a) aromatic (17 percent by weight) enriched kerosene or (b) a petroleum condensate or (c) a blend of (b) and crude oil slurries, were prepared by phase transfer by first injecting molten sulfur into an aqueous liquid such as water and thereafter contacting the slurry thus formed with hydrocarbons (a), (b) or (c) to effect phase 2. Sulfur-hydrocarbon slurries thus formed in the presence of 5 the water and an asphaltene additive of the present invention do not corrode or plug pipelines. Instead of using the phase transfer technique for making the slurry, the molten sulfur can be injected in the hydrocarbons (a), (b) or (c) directly and thereafter admixed with the aqueous solution and additive.

An advantage of the present process for transporting through pipelines sulfur-liquid hydrocarbon slurries is that the slurry can be also prepared by directed injection of molten sulfur into a suitable liquid hydrocarbon as described in U.S. Pat. 2,798,772 and injecting therein a small amount of water and an asphaltene additive so as to prevent corrosion and plugging of the line. Either process as well as other processes can be used to make the sulfur-liquid hydrocarbon slurry depending on the availability of the liquid carriers. Thus, where water is available the first process can be used and if not, the second one can be used.

The corrosive effect of added or adventitious water on sulfur-liquid hydrocarbon slurries is evident from the data presented in Table l and the selectiveness and unexpected effect of asphaltenic additives of this invention as corrosion preventive agents is shown in Table 2. I

The slurry tested comprised 40 percent by weight sulfur and 60 percent hydrocarbon and the conditions for the corrosion test were as follows:

Corrosion by Sulfur Slurries Conditions:

150 ml. magnesia bottles rotated at r.p.m. in EPR bottle I'OlfltOl'.

120 grams of slurry added to each bottle. Slurry concentration =40 percent sulfur.

Table l Sulfur Slurry Corrosion as a Function of Water Cqn sn esi w.

As ABQTEUYJWZ'JOJ sulfur/kerosene with 17 w/o aromatics Conditio ris:

Water Concentration. w/o" Corrosion Rate. mils/yr."

Concentration ofadde d Wa te r, Q55. T From weight loss and exposure time. Corrosion rates have not been corrected for weight loss due to cleaning.

Table 2 Effect of Asphaltenes on Sulfur Slurry Corrosion Conditions: A: in Table l. 40 w/o Jumping Pound sulfur! kerosene with aromatics Additive" Corrosion Rate, rn.p.y."

Medicine River Crude Asphaltenes 210 p.p.m. 8.8

0.1 who 5 Asphalt 0.06 w/o containing p.p.m.

Asphaltenes 4,5

From weight loss and exposure time. Corrosion rates have not been corrected for weight loss due to cleaning.

b Produced by heptane precipitation.

' Additions are basis oil phase. v

At the terminal end of the line the water phase can be readily removed by phase separation and the sulfur can be removed from the liquid hydrocarbon by suitable means such as described in U.S. Pat. No. 2,798,772 and the sulfur purified by methods as described in U.S. Pat. No. 2,809,885 or as described in the copending patent application Ser. N 0.

684,507, filed Nov. 20, 1967 which matured as U.S. Pat. No. 3,489,677 which comprises treating oil contaminated sulfur with an aqueous solution containing a mixture of alkali hydrosulfide and corresponding hydroxide, e.g., ammonium hydrosulfide and ammonium hydroxide, or by other suitable means such as sulfur can be recovered from the oil slurry by filtration of molten sulfur and liquid-liquid extraction with a hydrocarbon solvent containing 10-50 percent by weight aromatic. Thus, at the receiving terminal the sulfur slurry can be filtered and washed. The recovered sulfur is then melted and purified by liquid-liquid extraction with an aromatic hydrocarbon such as cumene. Also, if desired, the filtered sulfur can be steam stripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described method may be made within the scope of the appended claims without departing from the spirit of the invention.

1 claim as my invention:

1. A method of transporting sulfur through a pipeline to a terminal preventing corrosion and without plugging the line comprising:

a. injecting from 10percent to 75percent of molten sulfur into a liquid hydrocarbon to form a sulfur-liquid hydrocarbon slurry;

b. mixing slurry (a) with from 0.1 percent to 10 percent of an aqueous solution containing from about 10 to about 5000 p.p.m. of an asphaltenic compound;

c. injecting the slurry (a) and solution (b) into a pipeline;

and,

d. transporting the sulfur-hydrocarbon slurry and aqueous solution mixture through a pipeline to a terminal station.

2. The method of claim 1 wherein the liquid hydrocarbon of (a) contains aromatic components and the asphaltenic compound is selected from the group consisting of oil-soluble asphalt, asphaltenes, asphaltogenic acids, petroleum resins and mixtures thereof.

3. The method of claim 1 wherein solution (b) is injected into the slurry (a) after the slurry (a) has been injected into a pipeline.

4. The method of claim 1 wherein the slurry- (a) contains l075 percent by weight sulfur and the balance being a liquid hydrocarbon containing from l030 percent aromatic com ponents and the amount of solution (b) added to slurryjg) is from 0.1 to 10 percent by weight water basis total slurry and from 20 to 2000 p.p.m. of an asphaltenic material basis oil phase.

7 v 5. The method of claim 4 wherein solution (b)iswat er containing 20-2000 p.p.m. of asphaltenes basis oil phase admixed with slurry (a) in amounts of from 1 percent to 5 percent by weight basis total slurry.

6. The method of claim 1 wherein the sulfur-liquid hydrocarbon slurry is separated into its component parts at the terminal end of the pipeline. 

2. The method of claim 1 wherein the liquid hydrocarbon of (a) contains aromatic components and the asphaltenic compound is selected from the group consisting of oil-soluble asphalt, asphaltenes, asphaltogenic acids, petroleum resins and mixtures thereof.
 3. The method of claim 1 wherein solution (b) is injected into the slurry (a) after the slurry (a) has been injected into a pipeline.
 4. The method of claim 1 wherein the slurry (a) contains 10-75 percent by weight sulfur and the balance being a liquid hydrocarbon containing from 10-30 percent aromatic components and the amount of solution (b) added to slurry (a) is from 0.1 to 10 percent by weight water basis total slurry and from 20 to 2000 p.p.m. of an asphaltenic material basis oil phase.
 5. The method of claim 4 wherein solution (b) is water containing 20-2000 p.p.m. of asphaltenes basis oil phase admixed with slurry (a) in amounts of from 1 percent to 5 percent by weight basis total slurry.
 6. The method of claim 1 wherein the sulfur-liquid hydrocarbon slurry is separated into its component parts at the terminal end of the pipeline. 